Small firearms with exchangeable barrel

ABSTRACT

An apparatus for detachably securing a firearm barrel with a receiver flange of a receiver assembly and characterized in that the receiver flange is longitudinally slit so as to permit the flange to be circumferentially constricted into clamping engagement with the barrel.

ite tates Patent irkenhageh et al.

SMALL FIREARMS WITH EXCHANGEABLE BARREL Manfred Birkenhagen,Eckernforde, Germany; Manfred Birkenaen, Eckernforde, Germany Inventors:

Assignee: J. P. Sauer & Sohn GmbH, Eckernforde, Germany Filed: Mar. 22,1971 Appl. No.: 126,441

Foreign Application Priority Data Nov. 25, 1970 Germany ..P 20 57 995.7

U.S. C1. ..42/75 1; Int. Cl ..F4lc 21/00, F411. 23/00 Field of Search..42/75 B, 75 A, 77;

Primary Examiner-Benjamin A. Borchelt Assistant ExaminerC. T. JordanAttorney-Burns, Doane, Swecker & Mathis [57] ABSTRACT An apparatus fordetachably securing a firearm barrel with a receiver flange of areceiver assembly and characterized in that the receiver flange islongitudinally slit so as to permit the flange to be circumferentiallyconstricted into clamping engagement with the barrel.

12 Claims, 8 Drawing Figures SMALL FIREARMS WITH EXCHANGEABLE BARRELGENERAL BACKGROUND, OBJECTS, AND

SUMMARY OF INVENTION The invention relates to a gun with exchangeablebarrel and in which the barrel rear end is inserted releasably in acorresponding recess of a receiver flange with an axial stop.

Customarily the barrel and the casing, or receiver, of small arms,especially guns, are connected with each other by means of aself-locking attaching thread. Since this connection must be very tightbecause it influences the performance of the firearm, it is not possibleby simple means to exchange the barrel of the firearm without therebeing the necessity afterwards of reworking" the firearm and zeroing itin again.

A construction has been known where basically the exchange of the barrelwith simple means is possible without subsequent reworking, whereby,however, the receiver flange, screwed tightly with the barrel, isseparate from the remaining body of the receiver. In that case, however,the barrel is screwed together with the receiver and stock by means oftwo screws, as a result of which the vibrations of the barrel developingduring cartridge detonation will be prevented from spreading freely.According to experience, however, the pre-supposition for goodperformance and for a constant alignment entails a freely vibrating orunrestrained barrel.

The present invention is based on the object of producing a gun with anexchangeable barrel, where the exchange of the barrel is possible withthe help of a simple tool without special auxiliary devices. Undercertain circumstances, it is possible, without any tool, to effect suchan exchange. Beyond this, no reworking is necessary after the exchangeand, further-more, the performance of the gun and the future position ofthe firearm will not be influenced disadvantageously. Further, thisinvention recognizes that one must avoid an arrangement wherein, becauseof a connection between the barrel and the front part of the stock via asecond attaching screw, the working of the woodof the front part of thestock could have an adverse effect on the future position of thefirearm.

According to the invention this problem is solved, in the case of a gunof the above mentioned type, by the fact that the receiver flange has alongitudinal slit in its bottom side, developed in a reinforced manneras a support and facing the stock, and that tightening elements willtighten the sides releasably facing each other along the longitudinalslit.

Therefore, a gun has been produced where the barrel can be quicklyexchanged for another one with a different caliber and which also can bequickly and simply disassembled for the purpose of transportation. Inthis way a requirement will be met which in the case of drop barrel gunshas been satisfactory for decades but, which in the case of repeaterrifles, however, has not been satisfactory heretofore because of adifierent type of con-struction. The gunner will now be able to shootwith his gun shells of different calibers. He does not need to becomeaccustomed therefore to other dimensions of the stock all over again andwill not be influenced as a result in a disadvantageous manner inregardto his shooting skill.

Moreover, it is less expensive to procure exchangeable barrels merelyfor various calibers than it is to procure entirely new repeater rifles.The characterizing tightening connection between the receiver and thebarrel is also tight enough to be able to safely absorb the loads orstresses occurring during the cartridge detonation, including thevibrations which substantially influence performance.

It has, therefore, become possible to produce a quickly and simplyexchangeable barrel while maintaining a freely vibrating attachmentmode.

To this must be added, moreover, that the forces produced by thetightening will create a negative pretension or compression at thebreech end of the barrel, that is in the cartridge chamber. Thisnegative pre-tension acts counter to the forces occurring during thedevelopment of the shot, i.e., cartridge detonation. Therefore, theoutside dimensions of a repeater gun of the type according to theinvention, need not be any larger than those of known repeater guns. Thefirearm thus remains light and handy just like traditional firearms.

Preferably in the lower section of the longitudinal receiver flangeslit, removed from the barrel recess or socket, there is a supportacting as a counter support for the flange tightening elements.According to one embodiment, presented by way of example, this supportor restraining means may be constituted by a screw connecting the stockwith a receiver flange, which screw is screwed into a thread in thelongitudinal slit. This restraining means, however, can also be a T-shaped sliding block into which the screw connecting the stock with thesupport has been screwed. In this case, the sliding block pulls thesupport onto the stock.

In the case of this embodiment, by way of example, it will beadvantageous to provide a recess or blind hole in the barrel, on theperiphery of the cylindricalend of the barrel which is inserted into thereceiver flange. A cylindrical peg is inserted into this recess and arecess passing through the longitudinal slit. This peg is supported on acarrying surface of the sliding block. This results in the barrel beingsecured in axial and peripheral directions although it is also held bythe tightening.

Moreover, the cylindrical peg makes certain that the barrel will alwaysbe inserted in the same position in which it had been fitted into thefirearm.

The purpose of these different supports in the lower section of thelongitudinal slit is to avoid bending, or barrel flattening, forcesduring the tightening of the tightening elements, so that merelytangential forces will engage in the barrel at the place of tightening.

Instead of securing the barrel by way of a loose cylindrical peg and aslidable sliding block, it is also possible to provide a kind of bayonetlock between the barrel and receiver flange, including locking studs atthe rear end of the barrel and corresponding counter bearings or lugs atthe base of the recess of the receiver flange. With this construction, apositioning of the barrel which will always be the same upon barrelinsertion can be guaranteed.

Another possible mode of attachment is by way of a thread, knownper se,at the end of the barrel and in the recess of the receiver flange.However, this threaded joint does not need to be made as difficult asmost threads to operate because of the longitudinal slit and thetightening elements. In order to achieve a firm selflocking seat and, asa guarantee of the exact position of the barrel after each barrelexchange process, the tightening elements, developed as fitted bolts,tangentially intersect the threaded joint. Thus, the barrel will beadditionally prevented from twisting.

A particularly favorable embodiment, by way of example, which permitsthe exchange of the barrel without the assistance of any kind of tool,has a front part of the stock separate from the main stock. Thisfore-part can be flipped down by means of a tightening lever. Thereceiver flange constricting means of the tightening lever isconstituted by cam surfaces which are provided on the mounting eyes ofthe tightening lever. These cam surfaces act upon corresponding camfollower surfaces of the clamping sleeves, which follower surfaces areshiftable axially on means rotatably supporting the lever so as toinduce convergance of sides of the receiver flange slit. At the sametime and in order to avoid asymmetry, the tightening lever effectivelywill be arranged symmetrical in relation to the axis of the gun.

The lever supporting means may comprise a bolt provided on both sideswith knobs. On the shaft of .this bolt, the bearing eyes of the clampinglever are guided. These bearing eyes are supported by the knobs of thebolts. The clamping sleeves are inserted on the bolt between the cammeans of the bearing eyes of the clamping lever and the sides of theflange slit.

In this case, the cam or ramp surfaces may be oppositely orientedthreads or helical surfaces, whereby the tightened socket receivingbarrel will be loosened by flipping or pivoting down the front part ofthe stock. After release of an additional safety, the barrel can bepulled out of the socket in a forward direction.

DRAWINGS The invention is to be explained once more in detail on thebasis of the embodiments given by way of example, so that from it allthe details, advantages and characteristics of the invention will becomeclear.

FIG. 1 shows a first embodiment of the place of con-' nection betweenthe exchanged barrel and the receiver of the gun according to theinvention by way of example in the form of a longitudinal section;

FIG. 2 shows a section following line IIII in FIG. 1;

FIG. 3 shows a second embodiment with another type of attachment of thebarrel likewise in longitudinal section;

FIG. 4 shows a section according to line IV-IV in FIG. 3;

FIG. 5 is a presentation in longitudinal section of a third embodimentof the gun according to the invention by way of example;

FIG. 6 shows a section following line VIVI in FIG.

F IG. 7 shows a presentation in longitudinal section of a fourthembodiment of the gun according to the invention by way of example, witha pivotable front stock;

DETAILED DESCRIPTION The receiver 10 with breech bolt 11, firing pin 12and firing pin spring 13, as well as the exchangeable barrel 14, iscommon to all embodiments given by way of example. All other parts ofthe firearm which have no influence on the invention and on which theinvention does not exert any influence either, have been omitted for thesake of simplicity. The inside of the barrel has been made in thecustomary manner with a cartridge chamber 15 and a bore 16. Allembodiments have, in common, a slotted support disposed underneath anannularly developed receiver flange.

The support slit has the purpose of tightening the receiver flange, inresponse to the action of tightening elements which narrow the slit, sothat the end of barrel 14 introduced into the bore of the receiverflange will be firmly tightened but can be easily pulled out wheneverthe tightening elements are released. The axial and circumferentialdimensions of the tightening or constrictable connection between the endof the barrel and the bore of the receiver flange are selected such thatthe tightening or constricting forces are large enough to absorb theaxial forces occurring as a result of the strain from a shot, withoutany additional locking being required between the barrel and thereceiver.

First of all, we shall now describe the embodiment according to FIGS. 1and 2 presented by way of example.

The smooth cylindrical bore 21 of the receiver flange 20 has beenharmonized with a recessed end 22 of the barrel in such a way that inthe case of the receiver flange, when not tightened, provides atelescoping, gliding fit seat for barred end 22. Upon insertion of end22 of the barrel into bore 21 of the receiver flange, the abutmentcollar 23 on the barrel strikes against the front edge of the receiverflange, before the end of the barrel itself reaches the base of bore 21.

The barrel inserted this way into the receiver flange 20 is tightenedwith the help of tightening screws 24, 25. These screws lie with theirheads sunk in corresponding bores of stop or flange 26. By way of theirthreaded shafts, these screws are screwed into corresponding femalethreads 27 in the half of flange 26,

which is opposite the screw head. The support itself, as

mentioned previously, has been divided into two parts by a longitudinalslit 28, which is aligned with the central axis of the barrel endreceiving bore of generally cylindrical means 20. By the propertightening of screws 24 and 25, the clamping force of the receiverflange on the end of the barrel can be made so great that the barrelwill be seated completely firmly in the receiver and the connection canabsorb all axial forces occurring upon detonation of a cartridge.

In order to avoid the imposition of bending or travel flattening forceson the receiver flange 20 as a result of the screw tightening, there isa threaded bore 29 formed symmetrically in each half of clamping flange-means 26, and passing upwardly through slot 28. A

screw 30 is screwed into the lowest part of the slit via bore 29 andthus partially into the side walls of the two halves of the support 26,with which screw the receiver is screwed to the stock. With the supportprovided by screw or restraining means 30, which will prevent acompression of the slit by the tightening screws 24 and 25, one willperceive that, in fact, only tangential forces are imposed on barrel end22 during tightening between the receiver flange 20 and the end 22 ofthe barrel.

Even though the clamping forces of screws 24 and 25 will suffice to holdthe barrel 14 in the receiver 10, an axial safety will be provided whichbecomes effective when, in actual fact, the tightening mechanism has notbeen properly tightened. Accordingly, there are circumferentially spacedlock studs 31 distributed over the periphery of the end of the barrelwhich are rotatable to a position behind corresponding projections 32close to the base of bore 21. Thus, the barrel, first of all, will beinserted in socket 20, twisted counter to its final position. It willthen be turned or twisted to its position of use, whereby lock studs 31move behind projections 32. In order to assure an unequivocal positionof the barrel after its rotation, a stop screw 33 has been provided.This screw enters socket 20 from the outside and projects into the pathof the lock studs. Thus, upon twisting the barrel in FIG. 2 in aclockwise direction, and up to the stop 33, the barrel will then obtainits correct position in relation to the receiver.

The embodiment according to FIGS. 3 and 4 show generally a similarconstruction.

In this embodiment the offset (i.e., reduced) end 42 of the barrel islikewise inserted into a receiver flange 40 up to the extent permittedby engagement of a barrel abutment 43 with the end of the socket 40,while tightening elements 44, 45 of the bipartite stop 46 are loosened.In this case, also, a screw 50, serving for the attachment of thereceiver to the stock of the gun, engages with female threaded sides ofslit 48 in order to exclude any barrel bending or flattening forcesduring flange tightening.

In the present case, however, the prevention of axial movement betweenthe end 42 of the barrel and the receiver flange 40 is accomplished byway of a threaded connection 41 However, and in contrast to the knownconnections, and with loosened tightening screws 44, 45, the barrel caneasily be screwed into the receiver flange 40.

As a matter of safety, and for the purpose of an unequivocal fixation ofthe barrel in the receiver, the transverse bores for the tighteningscrews 44 and 45 have been disposed in such a manner that the screws,which have been developed partly with a cylindrical shaft 51, intersectconcave, cylindrical segment recesses formed to extend transversely ofthe connecting thread 41. As a result of this, the tightening screws 44,45 can be inserted and tightened only when the barrel has been screwedinto a quite definite axial position, namely the stop position, and intoa quite definite angular position, so as to align the thread recesses ofbarrel 1 4 with the bores for screws 44, 45. Thus, even in the case ofloosening of the tightening screws 44 and 45, the barrel still cannot beseparated from the receiver due to the intersection of screws 44, 45with the transverse recesses of thread means 41.

A development similar to the one in the first design is shown by theexample according to FIGS. 5 and 6.

Here too there is a receiver flange 60 with a smooth inside bore 61. Inthis bore, an end 62 of the barrel 14 is inserted up to the abutment ofits collar 63 with the front edge of the receiver flange 60.

A stop or flange means is provided with a longitudinal, vertical slit 68and includes transverse bores for the reception of tightening screws 64and 65. These screws are disposed approximately in the same position asin the example according to FIGS. 1 and 2.

The safety, and axial as well as angular fixation of the barrel in thereceiver flange is accomplished in this case in a different manner.

As FIG. 6 shows, the vertical flange means slit, in its lower section,has a T-shaped enlargement 71 in which there is a longitudinallyslidable sliding block 72. This sliding block 72 serves, for one thing,the purpose of preventing the excessive compression of slit 68 by thetightening screws, so that only tangential forces can be imposed on thecircumference of the barrel due to the screw induced constriction ofsocket means 60. The sliding block is fixed in an axial direction bymeans of attaching screw means 79, with which the receiver is screwedonto the gun stock.

Prior to tightening of the tightening screws 64, 65 and the insertion ofattaching screw 70, however, the restraining means or sliding block isslidable in an axial direction in its T-shaped slit. This permits acylindrical pin 73 or alignment recurring means to be slipped in, frombelow through second aligning recess means or fitted bore in the flangemeans, into engagement with a correspondingly fitted first aligningrecess means or blind hole 74 in the cylindrical end of the barrel, andthus fix the barrel both axially and in its angular position. Withcylindrical pin 73 completely inserted, the sliding block 72, with itsoffset end or restraining means 75, can be pushed along slit 71 todispose its offset end below the cylindrical pin so that the latter canno longer glide out of its fitted bore means. The axial fixation ofsliding block 72 is then accomplished by means of attaching screw beingscrewed into engagement with the portions of flange means 66 above block72.

Thus the barrel has been exactly aligned in the receiver and, moreoverin the case of a possible loosening of the tightening screws 64 and 65,it has been secured from dropping out.

Another solution again is in FIGS. 7 and 8.

End 82 of the barrel and receiver flange 80, inclusive of thearrangement of the lock studs 91 and counter elements or projections 92in the bore, are the same as the corresponding elements in the exampledescribed on the basis of FIGS. 1 and 2. The support 66 too is providedwith a vertical, longitudinal slit 88, which has in its lower portion, aT-shaped enlargement 93, as known already from the embodiment accordingto FIG. 5. Slot enlargement 93 receives a sliding block 94, into which ascrew 95 is threadably disposed for the attachment of the stock andsecuring of block 94.

In this case too, sliding block 94 serves to avoid the occurrence ofbending or barrel flattening forces during tightening of the receiverflange. The tightening of the receiver flange, however, in the case ofthe embodiment described here, is accomplished in a particularly simplemanner and is particularly practical for operation during exchange ofthe barrel.

A cylindrical tightening bolt 97, provided with heads 96, passes througha bore of support 86. A tightening lever 98, pointing longitudinallyforward, has been mounted with bearing eyes 99 joumaled on thetightening bolt 97.

shown by the embodiment Discs 100 have been provided, each of which isrotatably slidably supported on one side by a bolt head 96 and on theother side has a screw-shaped ramp surface. A transverse bore 101 in thesupport 86 has been provided with a frusto-conical enlargement on bothentry ends. Clamping sleeves 102 fit in these enlargements and havescrew-shaped or helical cam follower surfaces corresponding to theshapes of cam surfaces of the annular discs 100.

The annular discs 100 are rigidly connected with the bearing eyes 99 ofthe tightening lever. The effective distance between the outer surfacesof the clamping sleeves 102, acted on by discs 100, becomes smaller orlarger depending on the position of the lever upon pivoting of theclamping lever 98. The ramp surfaces are dimensionally harmonized insuch a way with regard to one another that, in the case of being swungupwards, the effective distance between the sides of the receiver asdefined by sleeves 102 is the smallest and, as a result of that, thesupport is clamped together. The distance becomes larger when the lever98 is pivoted downwards. At the same time, of course, the clampingconnection between the receiver flange 80 and end 82 of the barrel isloosened.

in this embodiment the fore-stock of the gun is subdivided into thefixed part 103 and a front part 104 that can be let down. Part 1041 isconnected by means of an attaching screw 105 with the clamping lever 98.However, there is no connectin between the front part of the stock andthe barrel.

The operation, in the case of exchanging barrels, is as follows.

The front part 104 of stock is pivoted or swung down, together withclamping lever 98. During this time, annular discs 100 are rotated inrelation to the clamping sleeves 102 and the clamping force exerted onthese sleeves and transmitted to the support declines. Now the barrelcan be twisted from its bayonet lock 91, 92 and can be pulled out fromthe cylindrical bore of the receiver flange 80. After insertion ofanother barrel, with for example a different caliber, which is put intothe inserting positon with the same bayonet catch, the front part ofstock 104 may be pushed up again. As a result, the clamping sleeves 102are again compressed by the camming cooperation between elements 100 and102 and a clamping force is exerted by the support on receiver flange80. Therefore, with this embodiment, it is particularly easy to carryout an exchange of the barrel.

To this advantageous development which makes possible a particularlyquick and simple exchange of the gun barrels, it must be added that, asa result of the negative pre-tension or compression exerted by theclamping forces of the receiver flange at the end of the barrel, therewill be a relieving counter effect operable to offset the radial forcesoccurring during firing of the shot. Thus, it will not be necessary toconstruct the entire arrangement, for reasons of strength, with moreexpensive material than that which is used in the case of known gunswith exchangeable barrels.

SUMMARY OF MAJOR ADVANTAGES AND GENERAL SCOPE OF INVENTION A principaladvantage of the invention resides in the provision of a uniquelysimplified barrel clamping arrangement which facilitates barrel exchangeand minimizes or eliminates the necessity for repeated zeroing-in.

Another advantage of the invention relates to the particularcircumferential clamping arrangement which is operable to imposetangentially directed barrel end securing forces, without inducingbarrel flattening or distortion.

The embodiment of the apparatus which is characterized by a leveractuated clamping device provides a uniquely simplified and reliablearrangement permitting an exchange of gun barrels without requiringrecourse to special tools or equipment or an increase in size or weightof gun components.

Those familiar with this disclosure and skilled in the firearms art mayrecognize additions, deletions, substitutions or modifications whichwould fall within the purview of the invention as set forth in theappended claims.

What is claimed is:

1. A firearm including exchangeable barrel means and comprising:

receiver flange means including barrel receiving socket means forreceiving a terminal end portion of said barrel means,

support means disposed generally beneath said socket means, and

longitudinal slit means formed in said support means and operable topermit circumferential contraction of said barrel receiving socketmeans;

said support means being operable to be connected with firearm stockmeans; and clamping means carried by said support means and operable toengage said flange means on opposite sides of said slit means, induceconvergence of said opposite sides of said slit means, and causecircumferential contraction of said barrel receiving socket means ofsaid flange means. 2. A firearm as described in claim 1 furtherincluding:

restraining means engaging outermost portions of said opposite sides ofsaid slit means, said restraining means being operable to restrainconvergence of said outermost portions of said opposite sides of saidslit means and thereby cause said clamping means to induce convergenceof inner portions of said sides of said slit means so as to producecircumferential contraction of said barrel receiving socket meanswithout imposing substantial barrel flattening forces on barrel meansreceived in said socket means. 3. A firearm as described in claim 2wherein: said restraining means comprises connecting means operable tointerconnect said support means with a firearm stock means; and

said restraining means further comprises screw means threadably engagingsaid opposite sides of said slit means, with said screw means extendingalong an axis which is generally perpendicular to a longitudinal axis ofsaid barrel means.

4. A firearm as described in claim 2 wherein:

said slit means has a generally T-shaped cross sectional configuration,extending transversely of the longitudinal axis of said barrel means;and said restraining means comprises:

block means having a generally T-shaped cross section slidably disposedin said slit means for sliding movement longitudinally of said barrelmeans, and threaded securing means threadably mounted in said blockmeans and operable to abuttingly engage generally downwardly facingsurfaces of said slit means. 5. A firearm as described in claim 1further including:

first, aligning recess means formed on the outer periphery of saidbarrel means; second, aligning recess means formed in said supportmeans; alignment securing means operable to extend through each of saidfirst and second recess means and thereby secure said barrel means in apredetermined position relative to said flange means; block meansslidably carried by said support means;

and restraining means carried by said block means and operable toabuttingly engage and secure said alignment securing means in said firstand second recess means. 6. A firearm as described in claim 1 furthercomprising:

bayonet-type locking lug means detachably interconnecting said barrelmeans and said flange means; and

stop means carried by said flange means and operable to maintain saidbayonet-type locking lug means in a barrel means securing position. 7. Afirearm as described in claim 1 further comprismg:

first threaded surface means carried by said flange means; and secondthreaded surface means carried by said barrel means and operable tothreadably engage said first threaded surface means; said clamping meansbeing operable to intersect said threadably engaged first and secondthreaded surface means and thereby maintain said first and secondthreaded surface means in a predetermined axial relationship.

8. A firearm as described in claim 1 wherein said clamping meanscomprises:

lever means pivotally connected with said receiver flange means;

rotary cam means carried by said lever means; and

cam follower means carried by constrictable portions of said supportmeans disposed laterally adjacent said slit means;

said cam means of said lever means being operable to cammingly cooperatewith said cam follower means to induce barrel means clampingconstriction of said barrel receiving socket means in response topivotal movement of said lever means toward said barrel means.

9. A firearm as described in claim 8 wherein:

said lever means comprises:

mounting eyes disposed on opposite lateral sides of said support means;said clamping means comprises bolt means transversely intersecting saidslit means and providing rotatable support for said eye means; and

said rotary cam means comprises a pair of rotary cams each supported byone of said eye means.

10. A firearm as described in claim 9 wherein said rotary cam meanscomprises a pair of generally helical cam surface means disposed onopposite sides of said support means and generally facing said slitmeans.

1 l. A firearm as described in claim 10 wherein:

said slit means has a generally T-shaped cross sectional configuration,extending transversely of the longitudinal axis of said barrel means;and

restraining means being carried by said support means and comprising:

block means having a generally T-shaped cross section slidably disposedin said slit means for sliding movement longitudinally of said barrelmeans, and

threaded securing means threadably mounted in said block means andoperable to abuttingly engage generally downwardly facing surfaces ofsaid slit means.

l2.-A firearm according to claim 1 wherein said receiver flange meansfurther includes:

means, in addition to said clamping means, for resisting axialdisplacement of said barrel means from said socket means.

1. A firearm including exchangeable barrel means and comprising:receiver flange means including barrel receiving socket means forreceiving a terminal end portion of said barrel means, support meansdisposed generally beneath said socket means, and longitudinal slitmeans formed in said support means and operable to permitcircumferential contraction of said barrel receiving socket means; saidsupport means being operable to be connected with firearm stock means;and clamping means carried by said support means and operable to engagesaid flange means on opposite sides of said slit means, induceconvergence of said opposite sides of said slit means, and causecircumferential contraction of said barrel receiving socket means ofsaid flange means.
 2. A firearm as described in claim 1 furtherincluding: restraining means engaging outermost portions of saidopposite sides of said slit means, said restraining means being operableto restrain convergence of said outermost portions of said oppositesides of said slit means and thereby cause said clamping means to induceconvergence of inner portions of said sides of said slit means so as toproduce circumferential contraction of said barrel receiving socketmeans without imposing substantial barrel flattening forces on barrelmeans received in said socket means.
 3. A firearm as described in claim2 wherein: said restraining means comprises connecting means operable tointerconnect said support means with a firearm stock means; and saidrestraining means further comprises screw means threadably engaging saidopposite sides of said slit means, with said screw means extending alongan axis which is generally perpendicular to a longitudinal axis of saidbarrel means.
 4. A firearm as described in claim 2 wherein: said slitmeans has a generally T-shaped cross sectional configuration, extendingtransversely of the longitudinal axis of said barrel means; and saidrestraining means comprises: block means having a generally T-shapedcross section slidably disposed in said slit means for sliding movementlongitudinally of said barrel means, and threaded securing meansthreadably mounted in said block means and operable to abuttingly engagegenerally downwardly facing surfaces of said slit means.
 5. A firearm asdescribed in claim 1 further including: first, aligning recess meansformed on the outer periphery of said barrel means; second, aligningrecess means formed in said support means; alignment securing meansoperable to extend through each of said first and second recess meansand thereby secure said barrel means in a predetermined positionrelative to said flange means; block means slidably carried by saidsupport means; and restraining means carried by said block means andoperable to abuttingly engage and secure said alignment securing meansin said first and second recess means.
 6. A firearm as described inclaim 1 further comprising: bayonet-type locking lug means detachablyinterconnecting said barrel means and said Flange means; and stop meanscarried by said flange means and operable to maintain said bayonet-typelocking lug means in a barrel means securing position.
 7. A firearm asdescribed in claim 1 further comprising: first threaded surface meanscarried by said flange means; and second threaded surface means carriedby said barrel means and operable to threadably engage said firstthreaded surface means; said clamping means being operable to intersectsaid threadably engaged first and second threaded surface means andthereby maintain said first and second threaded surface means in apredetermined axial relationship.
 8. A firearm as described in claim 1wherein said clamping means comprises: lever means pivotally connectedwith said receiver flange means; rotary cam means carried by said levermeans; and cam follower means carried by constrictable portions of saidsupport means disposed laterally adjacent said slit means; said cammeans of said lever means being operable to cammingly cooperate withsaid cam follower means to induce barrel means clamping constriction ofsaid barrel receiving socket means in response to pivotal movement ofsaid lever means toward said barrel means.
 9. A firearm as described inclaim 8 wherein: said lever means comprises: mounting eyes disposed onopposite lateral sides of said support means; said clamping meanscomprises bolt means transversely intersecting said slit means andproviding rotatable support for said eye means; and said rotary cammeans comprises a pair of rotary cams each supported by one of said eyemeans.
 10. A firearm as described in claim 9 wherein said rotary cammeans comprises a pair of generally helical cam surface means disposedon opposite sides of said support means and generally facing said slitmeans.
 11. A firearm as described in claim 10 wherein: said slit meanshas a generally T-shaped cross sectional configuration, extendingtransversely of the longitudinal axis of said barrel means; andrestraining means being carried by said support means and comprising:block means having a generally T-shaped cross section slidably disposedin said slit means for sliding movement longitudinally of said barrelmeans, and threaded securing means threadably mounted in said blockmeans and operable to abuttingly engage generally downwardly facingsurfaces of said slit means.
 12. A firearm according to claim 1 whereinsaid receiver flange means further includes: means, in addition to saidclamping means, for resisting axial displacement of said barrel meansfrom said socket means.